src/tools/fix-old-flex-code.pl

   1 #!/usr/bin/perl
   2 #----------------------------------------------------------------------
   3 #
   4 # fix-old-flex-code.pl
   5 #
   6 # flex versions before 2.5.36, with certain option combinations, produce
   7 # code that causes an "unused variable" warning.  That's annoying, so
   8 # let's suppress it by inserting a dummy reference to the variable.
   9 # (That's exactly what 2.5.36 and later do ...)
  10 #
  11 # Portions Copyright (c) 1996-2022, PostgreSQL Global Development Group
  12 # Portions Copyright (c) 1994, Regents of the University of California
  13 #
  14 # src/tools/fix-old-flex-code.pl
  15 #
  16 #----------------------------------------------------------------------
  17
  18 use strict;
  19 use warnings;
  20
  21 # Get command line argument.
  22 usage() if $#ARGV != 0;
  23 my $filename = shift;
  24
  25 # Suck in the whole file.
  26 local $/ = undef;
  27 my $cfile;
  28 open($cfile, '<', $filename) || die "opening $filename for reading: $!";
  29 my $ccode = <$cfile>;
  30 close($cfile);
  31
  32 # No need to do anything if it's not flex 2.5.x for x < 36.
  33 exit 0 if $ccode !~ m/^#define YY_FLEX_MAJOR_VERSION 2$/m;
  34 exit 0 if $ccode !~ m/^#define YY_FLEX_MINOR_VERSION 5$/m;
  35 exit 0 if $ccode !~ m/^#define YY_FLEX_SUBMINOR_VERSION (\d+)$/m;
  36 exit 0 if $1 >= 36;
  37
  38 # Apply the desired patch.
  39 $ccode =~
  40   s|(struct yyguts_t \* yyg = \(struct yyguts_t\*\)yyscanner; /\* This var may be unused depending upon options. \*/
  41 .*?)
  42         return yy_is_jam \? 0 : yy_current_state;
  43 |$1
  44         (void) yyg;
  45         return yy_is_jam ? 0 : yy_current_state;
  46 |s;
  47
  48 # Write the modified file back out.
  49 open($cfile, '>', $filename) || die "opening $filename for writing: $!";
  50 print $cfile $ccode;
  51 close($cfile);
  52
  53 exit 0;
  54
  55
  56 sub usage
  57 {
  58         die <<EOM;
  59 Usage: fix-old-flex-code.pl c-file-name
  60
  61 fix-old-flex-code.pl modifies a flex output file to suppress
  62 an unused-variable warning that occurs with older flex versions.
  63
  64 Report bugs to <pgsql-bugs\@lists.postgresql.org>.
  65 EOM
  66 }